Skeletal maturity is assessed commonly in research and in clinical practice. Most of the radiographs from which the widely used atlases of standards have been derived were taken before 1950 and the method of assessment used currently is essentially that of Todd (1937). The major objective of the present study was to develop a completely new method, for various areas of the skeleton, using existing serial radiographs of normal children. These radiographs are available in the files of The Fels Research Institute. This work has now been completed for the knee. The next step in this investigation is to develop a similar method for the hand-wrist. This will be based on the analysis of proven useful maturity indicators. Many of those described in the literature are not useful and will be excluded from the assessment scheme being elaborated. After the testing of indicators, observations are made on the whole sample of radiographs. These observations allow a determination of ages at which boundaries of the qualitative indicators are crossed. This information is combined with quantitative data (ratios) to obtain area skeletal ages of greater validity than those currently available. The method of scoring being applied provides, for the first time, the limits of accuracy of each assessment. BIBLIOGRAPHIC REFERENCES: Roche, A.F., Thissen, D. and Wainer, H.C. Skeletal Maturity: The Knee Joint as a Biological Indicator. Plenum Press, New York pp. 386, 1975. Roche, A.F., Roberts, J., and Hamill, P.V.V. Skeletal Age in United States Children, by Racial and Socio-Economic Factors, 6-11 Years. National Center for Health Statistics. Washington, D.C., U.S. Govt. Printing Ofc. Series 11, No. 149, 1-82, 1975.